A plain, middle-aged married man, Richard Sherman sends his wife Helen and his young son Ricky off to vacation at the seashore in Maine during a sultry summer in New York City. They escape but he must remain behind in the heat, to make money. He sees them off at the train station, promising to eat properly, and neither smoke nor drink. He will be sensible, not play around as soon as his wife leaves like so many other men. That is until he meets his new upstairs neighbor--subletting for the summer--a stunning, curvaceous, wide-eyed blonde with a giggly voice. Sherman is already prone to Walter-Mittyish fantasies, and in a flash his lively imagination goes into full gear as he battles the seven-year itch.